#define _CRT_SECURE_NO_WARNINGS 1
#include<iostream>
#include<algorithm>
using namespace std;
struct coin
{
	int m;
	int v;
}a[110];
bool cmp(coin x, coin y)
{
	return y.m * x.v > x.m * y.v;
}
int main()
{
	int n,t,sy,i;
	double sum = 0;
	scanf("%d%d",&n,&t);
	sy = t;
	for (i = 0; i < n; i++)
		scanf("%d%d", &a[i].m, &a[i].v);
	sort(a, a + n, cmp);
	for (i = 0; i < n; i++)
	{
		if (a[i].m > sy)
			break;
		sy = sy - a[i].m;
		sum += a[i].v;
	}
	if(i<n)
		sum += 1.0 * sy * a[i].v / a[i].m;
	printf("%.2lf\n", sum);
	return 0;
}